1. Field of the Invention
The present invention relates to a circuit for selectively driving pixel rows in an LCD display and more particularly to a row select driver circuit using thin-film transistors deposited on a substrate of the liquid crystal display.
2. Description of the Related Art
Displays using liquid crystal display (LCD) or similar devices include thin-film MOS transistors deposited on a glass substrate. At present, almost all commercially available active matrix liquid crystal displays (AMLCD) are unscanned.
An unscanned AMLCD requires one external lead for each column and row line. For example, a direct line interface driver for a black and white 768.times.1024 XGA computer display would require 1792 leads. The need for this great number of leads in the display drivers is a major problem which gets worse as the resolution and complexity of displays increase. Two major goals for solving the problem are to reduce the number of required input leads and to "integrate" the driver circuitry such as shift registers and latches directly onto the display substrate.
U.S. Pat. No. 5,034,735 discloses a driving apparatus using two transistors per pixel row for producing select and deselect signals and sequentially addressing them through the transistors' control gates. These transistors may be formed as thin-film transistors on a glass substrate along with a switching circuit 43, a switching signal generating unit 41, a scanning selection signal bus 411, and a scanning nonselection bus 412.
U.S. Pat. No. 5,157,386 discloses a circuit driving an active matrix liquid crystal display having M rows and N columns by video digital data of K bits. An analog switch capable of ON and OFF states receives a video voltage and a control signal and selectively outputs the video voltage to each column in response to a control signal. This is not a circuit for selectively driving the rows of a display.
U.S. Pat. No. 5,113,181 discloses a display apparatus comprising a plurality of pixels arranged in rows and columns. A data driver demultiplexer is disclosed.
The above-cited U.S. Pat. are the best known examples of relevant prior art known to the inventor. Almost all of the other commercially available active matrix liquid crystal displays are unscanned.